presentation Report
Ahmed_Jumaan
GroupPresentation.pptxPerovskite Rainbow Solar Cells
Ahmed Al Jamaan, Madeleine Adams, Truc Thanh Tran, Manasi Vyas
Hi everyone! My name is Madeleine (allow everyone else to introduce themselves), and we’re here to tell you about our product, a perovskite solar cell with rainbow quantum dot technology
Application Description
Our company is committed to developing a new type of solar cell using perovskite thin film technology, supplemented with varying sizes of quantum dots to enhance the harvesting of light from a wider variety of spectra, ultimately creating an efficient rainbow solar cell.
Madeleine
Solar Cells: Description and Current Applications
Description:
Solid structure technology that converts solar radiation into electrical energy
Also called photovoltaic cells
Supplies direct current (DC) through the cell as the battery
The voltage supplied by the cells alternate with any change in resistance
Applications include:
Generating electrical power from sunlight through solar panels
Solar lighting
Charging solar car batteries through car roof panels
Heating and cooling
Ahmed
Solar Cells is a solid Structure ……… it’s also called …… which supplies …… it does the same function of battery in terms of supplying direct current, but the difference between solar cells and battery is that the voltage supplied by…..
There are 4 important solar cell applications include….
There are many app for solar cells app include
Perovskite
Displays a variety of properties including superconductivity and magnetoresistance, and being easily synthesizable
Solar cell applications include a perovskite structured compound
Hybrid organic-inorganic lead or tin halide-based material as the light-harvesting active layer
Pros:
Ease of fabrication
Strong solar absorption
Low non-radiative carrier recombination rates
Madeleine
BEFORE: draw diagram and include quantum dot layer
Perovskite is actually a naturally-occurring mineral discovered in the 19th century in the Ural Mountains. The material itself is pretty unremarkable, however, it is the arrangement of atoms within its crystal that’s exciting for our company. The perovskite mineral consists of a crystal in which 3 atoms (Calcium, Titanium and Oxygen) are arranged in a specific repeating order. Today, and for our application, perovskites refer to any material that has that particular crystalline structure.
Perovskites inherently absorb more light than standard solar cell materials like silicon and thus have a higher theoretical limit of current that can be extracted from the material. And contrary to silicon, the spectrum of light absorbed by perovskites actually increases with temperature – ideal for outdoor usage. Moreover, once the absorbed light generates electrons within the Perovskite material, fewer of these electrons are lost thanks to uniquely low recombination mechanisms within the material. This has the impact of increasing both the current and voltage extractable from the device – important for achieving high efficiencies.
To turn the perovskite material into a solar cell, the material is simply deposited on top of a layer of titanium dioxide, which itself sits on a glass substrate along with a conducting film, either fluorine-doped tin oxide (FTO) films or indium–tin oxide (ITO) films. An additional material (called a hole transport medium) is added on top of the perovskite before adding a metal contact (generally gold or silver). This resulting structure also has quantum dots grown onto the titanium dioxide layer of the solar cell.
Perovskite Cont.
Tin Perovskite vs Lead Perovskite
Tin perovskite (CH3NH3SnI3): low toxicity, ideal choice of band gap
Lead perovskite (CH3NH3PbX3): high toxicity, greater stability when exposed to oxygen
Solution: A mixture of Sn and Pb perovskite
Madeleine
Minimum amount of energy required to get an electron excited
Perovskites are easily fabricated, cheap and abundant, and have a high efficiency of energy conversion
Quantum Dots
Tiny particles or nanocrystals of a semiconducting material with diameters in the range of 2-10 nm
They absorb photons and re-emit the photons at different wavelengths
Absorption and remission are directly related to size
Manasi: Essentially, when energy hits an atom, the electrons inside it get excited. When these electrons go back to their original energy state, the atoms emits the same amount of energy that hit it. This is because atoms have quantized energy levels. Quantum dots do the same trick—they also have quantized energy levels. When a photon hits it, the quantum dot emits a photon at the same wavelength. When these are made from the same material, they will give out different colors of light depending on how big they are.
Quantum Dots Cont.
Quantum dots can be classified between different types based on their composition and structure
Selecting the size and materials of our QDs allows us to tune the bandgap throughout most of the solar spectrum
Manasi: The biggest quantum dots produce the longest wavelengths (and lowest frequencies), while the smallest dots make shorter wavelengths (and higher frequencies); in practice, that means big dots make red light and small dots make blue, with intermediate-sized dots producing green light (and the familiar spectrum of other colors too). This is because a small dot has a bigger band gap (crudely speaking, that's the minimum energy it takes to free electrons so they'll carry electricity through a material), so it takes more energy to excite it; because the frequency of emitted light is proportional to the energy, smaller dots with higher energy produce higher frequencies (and shorter wavelengths). Larger dots have more (and more closely) spaced energy levels, so they give out lower frequencies (and longer wavelengths).
Quantum Dots Cont.
Options: SnS, PbS, CdSe → all have different band gaps
SnS, PbS: narrow band gap, optically active in the infrared and near infrared region
CdSe: a wide variety of applications, large surface area to volume ratio, efficient light absorber
Our selection: CdSe
Typically have higher orders of absorption than other typically used materials such as silicon
Generates higher photocurrents
Manasi
Rainbow Solar Cell
Idea: Use different sized quantum dots to harvest a larger section of the sunlight spectrum
Each quantum dot is tuned to a specific wavelength of light to enhance light absorption
Truc
solar cells made of different-sized quantum dots, each tuned to a specific wavelength of light.
Characterizing Rainbow Cells
Two main challenges to achieve maximum efficiency (greater than 30%):
Organizing the light harvesting nanostructures
Quantum dots should generate multiple charge carriers to be captured to generate photocurrent.
Solution:
Experiments in nanostructure and different-sized quantum dots assembled in an orderly fashion
Truc
Rainbow Cells Details
Four different sizes of quantum dots exhibited absorbent peaks at different wavelengths
3-nm quantum dots offered the best compromise: faster rate of electron convert and greater absorbance.
Truc
The researchers used four different sizes of quantum dots (between 2.3 and 3.7 nm in diameter) which exhibited absorbent peaks at different wavelengths (between 505 and 580 nm). The group observed a trade-off in performance corresponding with quantum dot size: smaller quantum dots could convert photons to electrons at a faster rate than larger quantum dots, but larger quantum dots absorbed a greater percentage of incoming photons than smaller dots. The 3-nm quantum dots offered the best compromise, but the researchers plan to improve both the conversion and absorption performances in future prototypes.
Read more at: https://phys.org/news/2008-03-quantum-dots-rainbow-solar-cell.html#jCp
Rainbow Cell Architecture
Small QDs on the outer edge of the cell absorbing blue light, larger QDs located in the inner layer absorbing red light
Nano architectures: Particle films and nanotubes experiments
Hollow 8000-nm-long nanotubes (both the inner and outer surfaces are accessible to quantum dots)→ more efficient electron transport than films
Schematic Diagram Illustrating Energy Level of Different-sized CdSe Quantum Dots and TiO2
Truc
Rainbow Cell Architecture (cont’d)
Materials: anchoring CdSe quantum dots on TiO2 nanotubes to create an ordered assembly of nanostructures
Truc
different-sized cadmium selenide (CdSe) quantum dots into titanium dioxide nanoparticles and nanotubes, showing a way to maximize the light absorption of quantum dot-based solar cells
Rainbow Cell Summary
Faster electron injection rate of small quantum dots and greater absorption range of larger quantum dots → higher efficiency
Absorb more wavelengths of light from the visible to the infrared region of the solar spectrum
Truc
CdSe cadmium selenide quantum dots inject electrons into TiO2 nanoparticles and nanotubes, thus enable the ability to tune the photoelectrochemical response and photoconversion efficiency via size control of CdSe quantum dots and (ii) improvement in the absorbance of more wavelengths of light from the visible to the infrared region of the solar spectrum
Current and Future Applications: Is a Nanotechnology Application Superior?
Current Application: Silicon Solar Cells
Most popular solar cells
Good efficiency (15-20%)
Relatively more expensive to make
Only absorbs in the red to near-infrared portion of the light spectrum
Future application: Perovskite Rainbow Solar Cells enhanced with QDs
Potential for high efficiency (greater than 30%)
Strong structure
Low-cost scalable solar cells to make.
Lighter weight for easy transportation
Has the potential to absorb a broader range in the light spectrum
Ahmed
We chose silicon solar cells as Current app and pervos as future app ... si which are most popular …. Which has a good eff that range btw 15-20%. Relatively It’s more expensive to make and it’s only absorbs ………
however, perv. Rainbow…… which has more potential for high eff which is greater than si…., stronger structure… low-cost scalable solar cells to make and lightweight for easy transportation .it has the potential of wide range in the light spectrum absorption.
Ahmed :
The graph shows steady growth over the years for all the different technologies includes Multijunction Cells, Single- junction GaAs, Crystalline Silicon Cells, Thin-film Technology, and Emerging Photovoltaic . As you the graph have different colors that refer to different technology ….. Multijunction Cells & Single- junction GaAs are present the theoretical efficiency that have been done in lab which have not been reached to the same efficiency in real env. .The efficiency numbers of the technologies that are actually implemented on the largest scale right now are still a step lower than what's in the lab, but those lab-modules might be the standard in the near future.
Graph Takeaways:
A gap in efficiency is present between theory and application
Goal: maintain the efficiency of PV solar cells while enlarging its surface area and using it in conditions subject to changes in weather
Perovskite is rapidly growing in efficiency
Thousands of chemical compositions to experiment with to determine max efficiency
Ahmed
And the goal is maintaining ……..
Major Limitations to Overcome
Lack of stability
Electrode materials cheaper than gold have a short lifespan
Deterioration occurs rapidly in the presence of moisture
Heavy encapsulation for protection can add to cost and weight
Scaling up
Toxicity
Breakdown products of perovskite are known to be toxic
May be carcinogenic (although this is still an unproven point)
Cadmium also has toxic properties
Stability in contact with moisture
Encase in acrylic or glass (counter to second bullet)
Scaling up - reported high efficiency ratings have been achieved using cells too small to be used in an actual solar panel
Toxicity- breakdown products of perovskite, particularly the lead perovskite compound, are known to be toxic. However, researchers are constantly seeking substitutions
Madeleine
Characterization and Manufacturing
Characterization will be performed on the materials and final product
Test materials need to be characterized the moment we get them to ensure purity and high performance
Materials need to be emitting in the right wavelength after absorbing photons
Once the solar cell is built, the unit needs to be characterized for light absorbance and reflectance from particles
Types of characterization for primary particles and final product:
Size distribution
Shape
Surface chemistry
Surface area
Absorption
Manasi
Size distribution/size: Our product is heavily dependent on having the right sizes for our quantum dots and the correct distribution of those sizes.
Shape: Any irregularities in shape will affect the final product efficiency.
Surface Chemistry: We want to check for impurities in our materials.
Absorption: Our product depends on a high absorption rate, so we need to test our both our final product and individual components for this property.
Characterizing nanomaterials
Scanning Tunnelling Electron Microscope:
Shows 3D image of a surface on an atomic level
Displays the distribution of particles in our final products
Measures conductivity of nanomaterial using an atomically sharp needle 1 nm away from the surface of a substrate and applying a voltage in between → Allows us to measure the charge conductance of our nanomaterials
Atomic Force Microscopy
Designed to measure local properties including friction, magnetism, surface chemistry, and shape of particles
Allows us to detect irregularly shaped nanoparticles, which can reduce the efficiency of a solar cell
Truc important for our products in term of distribution
Scan: measure conductant and distribution of particle
Atomic: detect nanoparticles
Characterizing Nanomaterials Cont.
Dynamic Light Scattering: Measures nanoparticle size
Particles undergo Brownian motion in solution → DLS monitors this phenomena by light scattering. The size of the particle is extracted from this information
Allows us to determine the size of our nanocrystals to see how that impacts absorption
Z-Scan: Measures nonlinear absorption and nonlinear refraction
A sample is translated through the beam waist of a focused beam and the power transmitted through the sample is measured
Allows us to create an absorption spectrum for our QDs and to thus measure their efficiency
Manasi
Top down or bottom up?
Bottom-up manufacturing - Quantum dots
CdSe QDs are produced by injecting cadmium and selenium precursor solutions into a heated growth solution, which form CdSe clusters that become continually growing QDs as the reaction progresses
Synthesis involves selective growth on patterned surfaces
A vapor-phase method will be used by growing layers in an atom-by-atom process
Self-assembly of nanostructures in material will be grown by molecular beam epitaxy
Enables selective growth on patterned surfaces
Madeleine
Continued
Bottom-up manufacturing: Perovskite Thin Film
Layer-by-Layer (LbL) technique is a process which can be regarded as a versatile bottom-up nanofabrication.
While doing research for our product, we can use spin coating, which is a deposition method used to deposit uniform thin films to flat substrates.
In an industrialized setting, slot die coating is more compatible with faster production:
It is a non-contact deposition technique which involves delivering a precise volume of material to a substrate by means of a meniscus between a die and the substrate
Conclusion
Perovskite is a stable material with amazing capabilities for converting light into energy
Quantum dots will increase the efficiency of our solar cell, ultimately creating a rainbow cell that is tunable to a wider spectrum of light
Perovskite is the next material that will break the silicon ceiling in solar cell manufacturing
RESOURCES:
Bawendi Group. (n.d). Massachusetts Institution of Technology. Introduction and Theory. Retrieved from: http://nanocluster.mit.edu/research.php#Synthesis_and_characterization
Cornell, C. (2016). Perovskite Solar Cell: Key To A Brighter Solar Future? Retrieved from: https://www.huffingtonpost.com/clayton-b-cornell/perovskite-solar-cell-key_b_11069628.html
Cha, Mingyang, et al. "Enhancing Perovskite Solar Cell Performance by Interface Engineering Using CH3NH3PbBr0.9I2.1 Quantum Dots." Journal of the American Chemical Society, vol. 138, no. 27, 26 June 2016, p. 8581–8587. Journal of the American Chemical Society, pubs.acs.org/doi/abs/10.1021/jacs.6b04519.
Han, J, et al. “Enhancing the Performance of Perovskite Solar Cells by Hybridizing SnS Quantum Dots with CH3 NH3 PbI3.” Small, vol. 13, July 10th, 2017. https://doi.org/10.1002/smll.201700953
Highly Oriented Low-Dimensional Tin Halide Perovskites with Enhanced Stability and Photovoltaic Performance. Yuqin Liao, Hefei Liu, Wenjia Zhou, Dongwen Yang, Yuequn Shang, Zhifang Shi, Binghan Li, Xianyuan Jiang, Lijun Zhang, Li Na Quan, Rafael Quintero-Bermudez, Brandon R. Sutherland, Qixi Mi, Edward H. Sargent, and Zhijun Ning. Journal of the American Chemical Society 2017 139 (19), 6693-6699 DOI: 10.1021/jacs.7b01815
J. Mater. A critical review on tin halide perovskite solar cells. Chem. A, 2017,5, 11518-11549
Kongkanand, Anusorn, et al. “Quantum Dot Solar Cells. Tuning Photoresponse through Size and Shape Control of CdSe−TiO2 Architecture.” ACS Publications, Journal of the American Chemical Society, 1 Mar. 2008, pubs.acs.org/doi/full/10.1021/ja0782706.
Matthew L. Landry, Thomas E. Morrell, Theodora K. Karagounis, Chih-Hao Hsia, and Chia-Ying Wang. (2014). Simple Syntheses of CdSe Quantum Dots. Journal of Chemical Education 91 (2), 274-279. DOI: 10.1021/ed300568e
Nanowerk. (n.d.). Retrieved October 17, 2017, from https://www.nanowerk.com/spotlight/spotid=45249.php
Valizadeh, Alireza, et al. "Quantum dots: synthesis, bioapplications, and toxicity." Nanoscale Research Letters, vol. 7, no. 1, 28 Aug. 2012, p. 480. National Center for Biotechnology Information, doi:10.1186/1556-276X-7-480.
Winter, M. (n.d.). Silicon: the essentials. Retrieved October 17, 2017, from https://www.webelements.com/silicon/
Zyga, Lisa. "Quantum Dots May Lead to Rainbow Solar Cell." 7 Mar. 2008, phys.org/news/2008-03-quantum-dots-rainbow-solar-cell.html.
